[Yaz4J](http://www.indexdata.com/yaz4j) is a wrapper library over the
client-specific parts of YAZ, a C-based Z39.50 toolkit, and allows you to use
the ZOOM API directly from Java. Initial version of Yaz4j has been written
-by Rob Styles from [Talis][http://www.talis.com] and the project is now
+by Rob Styles from [Talis](http://www.talis.com) and the project is now
developed and maintained at IndexData.
[ZOOM](http://zoom.z3950.org/api/zoom-1.4.html) is a relatively straightforward
API and with a few lines of code you can write a basic application that can
Here we will try to build a very simple HTTP-to-Z3950 gateway using yaz4j and
the Java Servlet technology.
-## COMPILING AND INSTALLING YAZ4J
+### COMPILING AND INSTALLING YAZ4J
Yaz4j is still an experimental piece of software and as such is not distributed
via Index Data's public Debian Apt repository and there is no Windows build (yet)
and Yaz (development package) installed on your machine. On Debian/Ubuntu you
can get those easily via apt:
- apt-get install sun-java6-jdk maven2 libyaz3-dev swig
+ apt-get install sun-java6-jdk maven2 libyaz4-dev swig
The Yaz4j's source code can be checked-out out from our
java -cp /path/to/yaz4j-*.jar -Djava.library.path=/path/to/libyaz4j.so MyApp
-## SETTING UP THE DEVELOPMENT ENVIRONMENT
+### SETTING UP THE DEVELOPMENT ENVIRONMENT
Setting up a development/runtime environment for a web (servlet) application is
a bit more complicated. First, you are not invoking the JVM directly, but the
application (inside the .war file) - it would try to load the library each time
you deploy the webapp and all consecutive deployments would fail.
-## WRITING A SERVLET-BASED GATEWAY
+### WRITING A SERVLET-BASED GATEWAY
With your servlet environment set up all that is left is to write the actual
application (peanuts :)). At IndexData we use Maven for managing builds of our
Java software components but Maven is also a great tool for quickly starting up
a project. To generate a skeleton for our webapp use the Maven archetype plugin:
- mvn -DarchetypeVersion=1.0.1 -Darchetype.interactive=false -DarchetypeArtifactId=webapp-jee5 -DarchetypeGroupId=org.codehaus.mojo.archetypes -Dpackage=com.indexdata.zgate -DgroupId=com.indexdata -DartifactId=zgate archetype:generate --batch-mode
+ mvn -DarchetypeVersion=1.0.1 -Darchetype.interactive=false \
+ -DarchetypeArtifactId=webapp-jee5 -DarchetypeGroupId=org.codehaus.mojo.archetypes \
+ -Dpackage=com.indexdata.zgate -DgroupId=com.indexdata -DartifactId=zgate \
+ archetype:generate --batch-mode
This will generate a basic webapp project structure:
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String zurl = request.getParameter("zurl");
- if (zurl == null || zurl.isEmpty()) { response.sendError(400, "Missing parameter 'zurl'"); return; }
+ if (zurl == null || zurl.isEmpty()) {
+ response.sendError(400, "Missing parameter 'zurl'");
+ return;
+ }
String query = request.getParameter("query");
- if (query == null || query.isEmpty()) { response.sendError(400, "Missing parameter 'query'"); return; }
+ if (query == null || query.isEmpty()) {
+ response.sendError(400, "Missing parameter 'query'");
+ return;
+ }
String syntax = request.getParameter("syntax");
- if (syntax == null || syntax.isEmpty()) { response.sendError(400, "Missing parameter 'syntax'"); return; }
+ if (syntax == null || syntax.isEmpty()) {
+ response.sendError(400, "Missing parameter 'syntax'");
+ return;
+ }
int maxrecs=10;
- if (request.getParameter("maxrecs") != null && !request.getParameter("maxrecs").isEmpty()) {
+ if (request.getParameter("maxrecs") != null
+ && !request.getParameter("maxrecs").isEmpty()) {
try {
maxrecs = Integer.parseInt(request.getParameter("maxrecs"));
} catch (NumberFormatException nfe) {
try {
con.connect();
ResultSet set = con.search(query, Connection.QueryType.PrefixQuery);
- response.getWriter().println("Showing " + maxrecs + " of " +set.getSize());
+ response.getWriter().println("Showing " + maxrecs + " of "+set.getSize());
response.getWriter().println();
for(int i=0; i<set.getSize() && i<maxrecs; i++) {
Record rec = set.getRecord(i);
mvn package
The resulting .war archive is located under `target/zgate.war`, we can deploy
-it on tomcat (e.g by using the /admin Tomcat admin console) and test by issuing
-the follwoing request with your browser or curl
+it on tomcat (e.g by using the `/admin` Tomcat admin console) and test by
+issuing the following request with your browser or curl
(assuming Tomcat is running on localhost:8080):
http://localhost:8080/zgate/?zurl=z3950.loc.gov:7090/voyager&query=@attr%201=7%200253333490&syntax=usmarc
That's it! You just build yourself a HTTP-to-Z3950 gateway! Just be careful
with exposing it to the outside world - it's not very secure and could be
easily exploited. The source code and the gateway's Maven project is available
-in the Yaz4j's Git repository under examples/zgate. In the meantime, IndexData
+in the Yaz4j's Git repo under `examples/zgate`. In the meantime, IndexData
is working on a Debian/Ubuntu package to make the installation of Yaz4j and
Tomcat configuration greatly simplified - so stay tuned!. If you are interested
in Windows support - e.g. Visual Studio based build or an installer - please
projects / yaz4j-moved-to-github.git / blobdiff